Lattice microstructures are arrays of beams and trusses arranged three-dimensionally (“3D”) in crisscrossed and/or diagonal patterns. Various geometries can be used depending on the application of the lattice. For uses requiring strength and support, a close-knit structure is preferred. For uses requiring some flexibility, patterns with trusses spaced apart are preferred.
There are notable methods of creating 3D microstructures. One such method is stereolithography, which is a bottom-up, layer-by-layer approach.
Another method utilizes one or a few optical waveguides, in which an initial area of polymerization in a photo-sensitive monomer will trap a light and guide it to a tip of the polymerized region due to an index of refraction change.
The concept of using 3D printing technology in footwear has been investigated in certain specific applications. For example, 3D printed material formed having a lattice structure has been used as a midsole. In some applications, to attain the necessary flexibility, the lattice structure is formed with various gaps and breakage in the structure, which results in a non-uniform lattice structure.
Other attempts to use 3D printing in midsoles are described in U.S. Pat. No. 6,763,611. In this application, the midsole has a lattice structure with a plurality of connectors and masses to attenuate and distribute ground reaction forces as a person walks, but the structure is not a microstructure and there is no description of forming the structure from a UV curable monomer with varying strength and flexibility properties. There is also no suggestion to incorporate the lattice structure into other parts of the footwear, such as the upper, tongue, vamp, eyelets, and eye stays.
U.S. Pat. No. 8,726,540 describes footwear with a sole having a grid pattern, in which channels are disposed in the pattern to promote flow of loose water off the sole, but there is no description of forming the structure from a UV curable monomer with varying strength, flexibility, and permeability in targeted regions of the structure.
European Patent App. No. 2,777,420 describes a shoe with a lattice midsole having a plurality of zones, each zone differing from one another in height to promote improved foot movement. The lattice midsole is made of a nylon polymer, but there is no description of forming the structure from a UV curable monomer and no description or suggestion of additional properties of their lattice midsole, other than providing varied height in the structures.
U.S. Pat. No. 5,632,057 describes a method of making orthotic devices for footwear using UV curing technology, in which light of a particular wavelength from a light source passes through a light table to cure a conformable device around a person's foot, but there is no description of a microlattice structure with different utilizations for footwear, padding, and insulation.
U.S. Pat. No. 9,017,806 describes a lattice microstructure with microstruts extending in different directions and sandwiched between two platforms to form a shoe insole, but there is no description or suggestion to incorporate the lattice microstructure into other shoe components. There are also no specifics given regarding how to use lattice microstructures for padding or insulation, such as a particular shape or structure.
Thus, is may be desirable to utilize lattice microstructures formed from a UV curable monomer with varying strength, flexibility, and permeability in targeted regions of the structure to produce other shoe components, such as the upper, tongue, vamp, quarters, and/or closure systems (i.e., laces), in a quick and efficient manner and with tunable properties ranging from strong, durable, flexible, and breathable.